Phonological processing and speech production in preschoolers with speech sound disorders

Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Communication Sciences and Disorders


Speech sound disorders, Preschool, Atypical errors, Phonological awareness, Phonological processing

Subject Categories

Communication Sciences and Disorders | Medicine and Health Sciences


Some children with speech sound disorders (SSD) have difficulty with literacy-related skills. In particular, they often have trouble with phonological processing, which is a robust predictor of early literacy. This study investigates the phonological processing abilities of preschoolers with SSD and uses a regression model to evaluate the degree to which these abilities can be concurrently predicted by types of speech sound errors.

Forty-three English-speaking preschoolers (ages four to five) with SSD of unknown origin participated in an assessment of phonological processing skills and speech sound production. Productions elicited on a 125-item picture naming task were phonetically transcribed, and errors were coded in two ways: (1) according to Percent Consonants Correct (PCC), which weights all consonant errors equally, and (2) according to a three-category system: typical sound changes, atypical sound changes, and distortions. Phonological awareness (PA) was assessed via rhyme matching, onset (initial consonant) matching, onset segmentation and matching, and blending. Phonological memory was assessed using a syllable repetition task. Children also rapidly named pictures of monosyllabic and disyllabic words.

Results showed that performance on a PA composite score could be predicted, in part, by vocabulary and age (about 33%). Atypical sound changes were found to account for additional variance in PA (another 6%), but distortions and typical errors did not account for significant variance in PA. Thus, use of more atypical sound changes was associated with poorer performance on PA tasks. When the same consonant errors were classified using PCC, speech sound errors were not found to predict significant variance in PA. Atypical sound changes also significantly predicted variance in phonological memory (about 31%) and rapid naming (about 10%) tasks beyond what had already been predicted by vocabulary and age.

The results support the notion that poorer performance on phonological processing tasks is associated with lower receptive vocabularies and production of more atypical speech sound changes. Results are interpreted in the context of the accuracy of phonological representations. Thus, atypical sound changes are seen as reflecting poorly specified internal representations of the sound features of words.


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